Cycles Render Material with black result [this is a bug; no problem with 2.77]
Your card is not fully supported by Blender.

From the Wiki:


  Radeon HD 7000 series (southern islands)   | Windows 7 x64 | Catalyst Beta 15.04   | Works (Not all features)


To confirm that this is the problem, disable GPU render and use CPU render, and the problem should go away. CPU will be MUCH slower, but it will support all features.

If the problem still exists with ONLY CPU rendering, then this is not the right answer.